“The study of any new science,” says Alexander v. Humboldt, “may be compared to a journey to distant lands. Before starting in company with others, the question as to the practicability of the journey is raised; while examining one's own powers, the qualities of fellow-travellers are looked upon with distrust. It is feared—perhaps without just reason—that they might cause unpleasant detention. In our time the difficulties of an undertaking of this kind are much diminished. Any confidence is founded on the bright blossoming state to which natural sciences have grown, their wealth being no more the abundant quantity, but the concatenation of what has been observed.”